1. Technical Field
The present invention pertains to the detection of substances.
2. Description of Related Art
Detection of substances plays an important role in the health and safety of individuals as well as the community at large. With respect to safety, detection of controlled substances, for example, is especially critical at points of entry into countries, transportation hubs, sensitive facilities (e.g., nuclear and other power plants) and buildings. Securing transportation hubs such as, for example, airports, bus and train stations and cargo and passenger ship terminals from controlled substances such as, for example, explosives, nuclear material, drugs such as drugs of abuse, pathogens and food and their component parts has been complicated by the large volume of luggage and other cargo moved through airports each day.
Various detection systems have been developed for the detection of explosives and controlled substances. Some techniques utilize radiation to inspect cargo such as, for example, both checked and carry-on luggage and other articles. These techniques often involve cumbersome and expensive equipment and visual inspection, which can be time-consuming and hazardous to individuals supervising the inspection. Accordingly, physical inspection, although a widely practiced and important technique, is slow, cumbersome, labor intensive and dependent on the training of the individual conducting the inspection. Current techniques include indirect methods that rely on the presence of vapor emanating from suspect material. One such indirect method, for example, employs dogs trained to sniff preferentially for explosives and narcotics. Techniques other than bulk surveillance are directed at detection of trace amounts of chemical substances adhering to an object such as, for example, clothing and baggage. Trace detection techniques for detecting explosives include, for example, chemiluminescence methods, fluorescence methods, light absorption methods, ion mobility methods, chromatographic methods and mass analysis methods.
Another area of interest is the detection of occupational and environmental substances such as pollutants, contaminants and other substances of interest. Numerous applications require the determination of the presence or absence of one or more substances in a sample. In a particular example, the presence or absence of a substance in a fluid sample may be required such as, for example, liquid or gaseous effluent or emissions from stationary or mobile sources. One important area is the detection of vehicle malfunctions such as, for example, substances leaking from various vehicle parts that include, e.g., engines, drive shafts, exhaust systems and components of electrical systems. Monitoring levels of volatile organic compounds is another important environmental area. Detection of chemical hazards such as carbon monoxide leaks and nature gas leaks is of great interest.
With regard to health, the clinical diagnostic field has seen a broad expansion in recent years, both as to the variety of materials of interest that may be readily and accurately determined, as well as the methods for the determination. Convenient, reliable and non-hazardous means for detecting the presence of low concentrations of materials in liquids is desired. The need to determine many analytes in blood and other biological fluids has become increasingly apparent in many branches of medicine. In endocrinology the knowledge of plasma concentration of a number of different hormones is often required to resolve a diagnostic problem or a panel of markers for a given diagnosis where the ratios could assist in determining disease progression. An even more pressing need is evident in other areas such as allergy testing and the screening of transfused blood for viral contamination or genetic diagnosis.
There remains a need for simple devices and methods for the accurate, sensitive and relatively quick and inexpensive detection of substances. The devices should not have external power supply requirements and should be useable in situ at both proximate and remote locations with remote detection of signal being desirable.